Solving Node.js Memory Leaks with a Simple Debugging Guide

1. Increasing Heap Memory: Is It a Solution?

Many people choose to increase heap memory to solve memory leak issues. However, this is not always the best solution.

Heap Memory Structure

The V8 engine of Node.js manages memory efficiently by dividing it into Young Generation and Old Generation. During this process, it uses the Mark and Sweep algorithm to remove unused objects. However, objects with remaining references stay in heap memory.

For example, arrays or objects declared as global variables cannot be removed by the garbage collector, leading to memory leaks. This means that increasing heap memory alone will not solve the problem.

Increasing heap memory to solve memory leaks is only a temporary solution.

2. Debugging Memory Leaks

To solve memory leaks, effective debugging is necessary. Node.js provides various debugging tools, and among them, profiling using Chrome’s inspect tool is very useful.

Debugging Methods

• Heap Snapshot: Records the current heap memory usage.
• Timeline: Periodically records heap memory usage and shows the changes in a graph.
• Sampling: Records heap memory usage over a long period through sampling.

Using the timeline helps to easily identify points where memory leaks occur.

Finding the Culprit of Memory Leaks

Debugging can reveal the cause of memory leaks. It is crucial to find the objects causing leaks by comparing shallow size and retained size.

3. Preventing Memory Leaks with the `using` Keyword

Recently introduced, the `using` keyword is very useful for preventing memory leaks. By using it, you can manage the lifecycle of objects and automatically release unnecessary memory.

Instead of `const`, use `using` to declare variables, and perform cleanup through `Symbol.dispose()`.

The `using` keyword is a powerful tool to prevent memory leaks.

In Conclusion

Memory leak issues can cause severe problems like performance degradation and server crashes. The heap memory structure, debugging methods, and the `using` keyword introduced today can effectively solve these problems. When you encounter memory leaks in your work, use these methods to resolve the issue. We hope this helps in your development journey. Thank you.